Recently, the Internet has become popular, leading to an increase in the number of users who exchange various data with other users over the Internet.
However, for example, when a user wishes to send a certain image to an apparatus of another user, it has been the case that mutual connection is essentially prohibited due to difference between the capabilities of a device of a user and a device of another user, resulting in a failure in transmitting image data.
In order to prevent this situation, a user must check the capability of a device at the other end in advance.
For example, in the case of streaming, RTSP (Real Time Streaming Protocol) (Real Time Streaming Protocol, IETF RFC 2326, April 1998, <http://www.ietf.org/rfc/rfc/2326.txt>) defines use of SDP (Session Description Protocol) (SDP: Session Description Protocol, IETF RFC 2327, April 1998, <http://www.ietf.org/rfc/rfc/2327.txt>) as a method of exchanging parameters for streaming between a server and a client.
However, RTSP does not define a specific method of exchanging parameters, resulting in a failure to overcome the problem that data cannot be exchanged reliably between a server and a client.